The universal rise of bacteria, fungi and other biological contaminants resistant to antimicrobial agents presents humanity with a grievous threat to its very existence. Since the advent of sulfa drugs (sulfanilamide, first used in 1936) and penicillin (1942, Pfizer Pharmaceuticals), exploitation of significant quantities of antimicrobial agents of all kinds across the planet has created a potent environment for the materialization and spread of resistant contaminants and pathogens. Certain resistant contaminants take on an extraordinary epidemiological significance, because of their predominance in hospitals and the general environment. Widespread use of antibiotics not only prompts generation of resistant bacteria; such as, for example, methicillin-resistant staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE); but also creates favorable conditions for infection with the fungal organisms (mycosis), such as, Candida. Given the increasing world's population and the prevalence of drug resistant bacteria and fungi, the rise in incidence of bacterial or fungal infections is anticipated to continue unabated for the foreseeable future.
Currently, available therapies for bacterial infections include administration of antibacterial therapeutics or, in some instances, application of surgical debridement of the infected area. Because antibacterial therapies alone are rarely curative, especially in view of newly emergent drug resistant pathogens and the extreme morbidity of highly disfiguring surgical therapies, it has been imperative to develop new strategies to treat or prevent microbial infections.
Therefore, there exist a need for methods and systems that can reduce the risk of bacterial infections, in/at a given target site, without intolerable risks and/or intolerable adverse effects to the host organism (e.g., mammalian tissues) other than the targeted microbial contaminants.
Generally, fiber optic phototherapy is an increasingly popular modality for the diagnosis and/or treatment of a wide variety of diseases. For example, in surgery, infrared laser radiation will often be delivered to a surgical site via a hand-held instrument incorporating an optically transmissive fiber in order to coagulate blood or cauterize tissue. Other uses for optical fiber-delivered radiation include treatment of atherosclerotic disease and prostatic disease. U.S. Pat. No. 4,878,492 issued to Sinofsky et al., incorporated herein by reference, discloses the use of infrared radiation to heat blood vessel walls during balloon angioplasty in order to fuse the endothelial lining of the blood vessel and seal the surface. Fiber optic delivery systems have been incorporated in endoscopic or catheter-based instruments to deliver radiation to a targeted biological site within a body lumen or cavity. Typically, the fiber optic phototherapy device is inserted through an instrument lumen or catheter for delivery in-vivo. Conventional optical fiber phototherapy devices can include an optical element, such as a focusing lens, that is coupled to the optical fiber by a cylindrical housing. The housing is typically a metallic band or cuff, constructed from stainless steel or gold that is sized to hold both the lens and the optical fiber. Alternatively, the housing can be glued to the optical fiber or can be threaded to facilitate connection to the fiber. Fluoropolymer housings in the prior art are thermally fused to the buffer of the fiber.
The performance of such conventional phototherapy devices incorporating a metallic housing has proven less than optimal. Additional problems associated with such conventional phototherapy devices include loosening of the optical element due to thermal cycling, as the metallic housing and the optical element, as well as the optical fiber, have significantly different thermal characteristics, such as the coefficient thermal expansion. Thus, during the application of radiation, the housing tends to expand greater than both the optical fiber and the optical element, resulting in loosening of the connection between the housing, the optical fiber and optical element, often breaking adhesive bonds. Thermal cycling can also result from sterilization procedures. Moreover, the effects of thermal cycling are magnified by the presence of the metallic housing which can absorb significant amounts of radiation from the optical fiber thereby further increasing the temperature of the housing. Many materials that are typically used for cylindrical cuff material absorb some laser radiation, despite the fact that they look “shiny”. For example, a stainless-steel housing can absorb approximately 40% of the incident radiation. Most of the prior art that describes the mounting of an optical element on the end of a fiber-optic teach the use of epoxies to hold all or some of parts of the tip together. The use of epoxies to hold the elements can be troublesome, since the epoxies have limited operating temperatures, may absorb part of the radiation, and darken as they degrade. When an epoxy darkens it absorbs more radiation which can then lead to a thermal runaway failure. Baxter et al, in U.S. Pat. No. 6,102,905 discloses an optical system that is held together by thermoforming the cuff onto a fiber with the identical material as the fiber buffer. This technique although effective, requires a complex thermoforming machine, and can damage the system's optical elements by exposing them to the 500 degrees C. it takes to melt the fluoro-polymers together. This temperature exceeds the recommended temperature for both the optical fiber cladding and the grin lens. This technique can also not be used when the fiber and cuff are not similar materials.
In some applications, it is important in phototherapy that a precise, uniform beam be employed for many conditions. Biophotonic responses are complex and unpredictable variations in illumination may result in unnecessary damage to healthy tissues by overheating, or the survival of malignant pockets by under treating, among other side effects. Uniform output illumination has been the goal of many of the fiber optic devices in the field of photonic medicine.
As the above described optical fiber phototherapy devices have proven less than optimal, it is an object of the present invention to provide improved phototherapy devices provide a precise, stable, controlled illumination of multiple wavelengths. A further object of the present invention is to provide phototherapy devices that inhibit the effects of heat cycling. A further object of the present invention is to provide phototherapy devices that are simple and inexpensive to manufacture.
Another object of the present invention is to provide an improved method of making a phototherapy device. Other general and more specific objects of this invention will in part be obvious and will in part be evident from the drawings and the description which follow.